CN107408614B - Light source - Google Patents

Light source Download PDF

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Publication number
CN107408614B
CN107408614B CN201680018704.9A CN201680018704A CN107408614B CN 107408614 B CN107408614 B CN 107408614B CN 201680018704 A CN201680018704 A CN 201680018704A CN 107408614 B CN107408614 B CN 107408614B
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Prior art keywords
light
led
output
semiconductor diode
light sources
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CN201680018704.9A
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CN107408614A (en
Inventor
N.A.M.斯威格斯
M.A.德萨姆伯
H.J.科内利森
F.M.H.克罗姆普韦茨
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Lumileds Holding BV
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Bright Sharp Holdings Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements
    • H01L33/60—Reflective elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/52—Encapsulations
    • H01L33/54—Encapsulations having a particular shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2105/00—Planar light sources
    • F21Y2105/10—Planar light sources comprising a two-dimensional array of point-like light-generating elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]

Abstract

It is presented a light source comprising: a plurality of LED light sources, each of the plurality of LED light sources having: a semiconductor diode structure adapted to generate light; and a light output section over the semiconductor diode structure adapted to output light from the semiconductor diode structure, the light output section having an area smaller than an area of the semiconductor diode structure; and an optically transmissive structure overlapping the light output parts of the plurality of LED light sources so as to receive light from the light output parts of the plurality of LED light sources, and having a light exit part adapted to output the received light. The area of the light exit portion of the optically transmissive structure is smaller than the footprint area of the plurality of LED light sources.

Description

Light source
Technical Field
The present invention relates to a light source, and more particularly to a light source including a plurality of semiconductor light sources.
Background
Semiconductor light sources such as Light Emitting Diodes (LEDs), high power LEDs, organic LEDs (oleds), and laser diodes are known to be energy efficient and small light sources with a small/low etendue (etendue), i.e., the product of the emission area and the solid angle of the emitted light. This means that these semiconductor light sources emit light from a relatively small area into a limited angular range.
Such semiconductor light sources may therefore be beneficial for applications requiring bright light sources. Typical example applications include projection systems, automotive lighting, camera flashes, and spotlights. For these examples, improved miniaturization is generally desirable. However, merely reducing the size of the semiconductor light source reduces the generated luminous flux.
It is known to obtain increased brightness from semiconductor light sources by means of a mixing box having a small aperture (i.e. a light output) from which light can escape. Fig. 1A and 1B illustrate a known LED-based light source 10 employing this concept, in which light generated by an LED 12 (on a die substrate 14) is circulated/reflected in a mixing box (formed of a material 16 having a high reflectivity) until it escapes via a small aperture 18. The aperture 18 is "small" simply meaning smaller than the LED 12, such that the aperture area AA(i.e., width W)AX LA) LED area A smaller than LED 12LED(i.e., width W)LEDX LLED）。
It is also known to form aperture 18 from a luminescent ceramic material or other phosphorescent material.
Disclosure of Invention
The invention is defined by the claims.
According to an aspect of the present invention, there is provided a light source including: a plurality of LED light sources arranged in a 2-dimensional array, each of the plurality of LED light sources having: a semiconductor diode structure adapted to generate light; and a light output section over the semiconductor diode structure adapted to output light from the semiconductor diode structure, the light output section having an area smaller than that of the semiconductor diode structure; and an optical transmission structure overlapping the light output parts of the plurality of LED light sources so as to receive light from the light output parts of the plurality of LED light sources, and having a light exit part adapted to output the received light, wherein an area of the light exit part of the optical transmission structure is smaller than a footprint area of the plurality of LED light sources.
The following concepts are proposed: light of increased brightness is obtained from a semiconductor light source having a mixing box with a small light output portion, and then re-emitted via a secondary light emission/exit surface of the optical structure. The optical structure may be used to limit the light output from the semiconductor light source and emit light via a more concentrated (e.g., smaller) area than the area occupied by the semiconductor light source.
Thus, embodiments may avoid the need for closely packed/spaced LED light sources, thereby reducing problems associated with thermal management of closely packed LED light sources. Furthermore, enabling the LED light sources to be spaced apart (while maintaining a small light emission surface of the light sources) can help alleviate addressability limitations associated with current density in the conductive addressing tracks.
Therefore, a concept for employing a high brightness LED light source is proposed, namely: the high brightness LED light source has light output sections having a smaller area than a light generating portion of the light source. By arranging the optical structure to collect and confine light from the LED light sources and then emit light again via the secondary light emission surface, a pixelated light source may be achieved in which the light emission surface comprises closely packed pixels outputting light from respective LED light sources that are spaced apart (e.g. less closely packed) such that they occupy a footprint area that is larger than the area of the light emission surface. It is therefore possible to use LED light sources to achieve pixelated light sources with high brightness properties and small spacings between light emitting pixels, which LED light sources are freed from the constraint of having to be closely packed with a spacing close to zero therebetween. The LED light source may alternatively comprise power LEDs with a high lumen output, which are spaced so as to be individually addressable and minimize thermal management problems.
The optical structure may be used to provide savings/reductions in the footprint size of the light exit/emission surface of the light source. Furthermore, it can be used to enable an increase in the footprint size of the LED light source, thereby enabling the use of more powerful LEDs and greater spacing between LEDs.
In other words, embodiments may provide a high-luminance light source including a plurality of high-luminance LED light sources that output light into an optical element that limits light and then output the light via a light exit/emission surface having an area smaller than a footprint area of the LED light source. The optical element may be adapted to redirect light from the LED light source such that the light output direction/orientation and/or position is altered or designed to enable tiling (tile) such that edges of the multiple light exit/emission surfaces may be closely aligned.
References to "footprint" or "footprint area" should be understood to refer to the shape and size of the area occupied. For example, the footprint of the plurality of LED light sources is understood to be the total surface/planar space or area occupied by the plurality of LED light sources. Thus, if the LED light sources are spaced apart from each other, the footprint of the LED light sources will comprise the entire area surrounding the LED light sources and the spaces therebetween.
In addition to reducing the footprint, an additional advantage of the optically transmissive structure is that it allows reshaping (re-shaping) of the original light distribution. For example, a 4x4 LED array may be deformed into a 2x8 array (or any other arbitrary shape) of light emitting surfaces.
The LED light source of the present disclosure can be any type of LED, such as flip-chip type (thin film flip chip), patterned sapphire substrate, top-connected/top-emitting, top-bottom connected. In addition, the light source may be used as a bare die or packaged.
The light output portion (or light emitting region) of the LED light source refers to a region toward or through which light from the LED is output (or emitted). Thus, the cavity or cavities of the LED light source may extend towards the light output section. The light output may for example be a region of a growth substrate (e.g. sapphire). Further, the light output direction is generalized to be a single direction (e.g., vertical in the drawing) along which light is output from the light output section. However, it should be understood that not all of the light output from the light output section may be precisely output in the output direction. Hence, the light output direction should be understood to refer to the general direction along which light is output from the light output section (e.g. extending away from the surface of the light output section).
In an embodiment, the optically transmissive structure may be adapted to confine (define) the received light by total internal reflection and thus reflect the received light towards the light exit section. For example, the optically transmissive structure may include one or more optical collimators.
In another embodiment, the optically transmissive structure may include a plurality of optical fibers positioned on top of the light output sections of the plurality of LED light sources. By employing an array of optical fibers positioned on the light output portion of the LED light source, light from the LED light source, for example, can be transmitted along the optical fibers and output from the optical fibers closer to the desired light exit plane and/or location.
The light output sections may be arranged such that there is substantially zero gap between adjacent edges of the light output sections. However, in practice, it may be difficult to perfectly align adjacent edges to have zero lateral gap. Thus, in embodiments, the light output sections may be laterally separated by a negligible or small amount. For example, there may be a lateral gap between adjacent edges of the light output portions of the two LED light sources, and the lateral gap may be less than 10% of the lateral width of the light output portion. In embodiments, it may be preferable to reduce such gap to a minimum value (e.g. less than 5% of the lateral width of the light output section, and even more preferably less than 1% of the lateral width of the light output section).
In an embodiment, the LED light source may further comprise a light reflecting structure at least partially enclosing a side surface of the semiconductor diode structure and adapted to reflect light from the semiconductor diode structure towards the light output section. Further, the light output section of the LED light source having the light reflection structure may include an aperture formed in the light reflection structure. Further, the semiconductor diode structure of the LED light source having the aperture formed in the light reflecting structure may include an optical enhancement material.
In one embodiment, the light output of at least one of the first and second LED light sources may comprise an optical enhancement material. The optical enhancing material may be a "color converting filler" such as a luminescent ceramic material or a phosphorescent material. This may further help to maintain etendue of the lateral emission region.
In an embodiment, the light source may further comprise a layer of optical enhancing material at least partially covering the light exit portion of the optically transmissive structure.
The optically transmissive structure may further comprise a fresnel structure at least partially overlapping the light output sections of the plurality of LED light sources.
Further, if an embodiment includes multiple cavities, some or all of the cavities may include (e.g., be filled with) different materials. As an example, some cavities may be filled with a first type of phosphor (e.g., converting blue to white) and other cavities may be filled with another type of phosphor (e.g., converting blue to red).
Embodiments may be employed in the field of automotive lighting and other fields/applications where high brightness lighting is required.
Therefore, according to an aspect of the present invention, there may be provided an automotive lamp including a light source according to an embodiment.
According to another aspect of the present invention, there may be provided a projection lamp including a light source according to an embodiment.
According to a further aspect of the present invention, there is provided a method of manufacturing a light source, the light source comprising a plurality of LED light sources arranged in a 2-dimensional array, each of the plurality of LED light sources having: a semiconductor diode structure adapted to generate light; and a light output section over the semiconductor diode structure adapted to output light from the semiconductor diode structure, the light output section having an area smaller than an area of the semiconductor diode structure, the method comprising the steps of: providing an optically transmissive structure overlapping the light output sections of the plurality of LED light sources for receiving light from the light output sections of the plurality of LED light sources, the optically transmissive structure having a light exit section adapted to output the received light, wherein the area of the light exit section of the optically transmissive structure is smaller than the footprint area of the plurality of LED light sources.
The optically transmissive structure may be adapted to confine received light by total internal reflection and thus reflect the received light towards the light exit section.
The step of providing an optically transmissive structure comprises positioning a plurality of optical fibers on top of the light output sections of the plurality of LED light sources.
Drawings
Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:
FIG. 1A is a cross-sectional view of a known LED light source;
FIG. 1B is a plan view of the known LED light source of FIG. 1A;
FIG. 2A is a side view of two LED-based light sources of the light source according to an embodiment, wherein the LED-based light sources are arranged in a spaced-apart arrangement;
FIG. 2B depicts the arrangement of the LED light source of FIG. 2A when viewed from above (i.e., in plan view);
FIG. 2C depicts a light exit portion of the optically transmissive structure of FIG. 2A, wherein the optically transmissive structure comprises a plurality of optical fibers, and wherein the light exit portions of the optical fibers are closely packed;
FIG. 3A is a side view of four LED-based light sources of a light source according to another embodiment, wherein the LED-based light sources are arranged in a spaced-apart arrangement;
FIG. 3B depicts the arrangement of the LED light source of FIG. 3A when viewed from above (i.e., in plan view);
FIG. 3C depicts a light exit portion of the optically transmissive structure of FIG. 3A, wherein the optically transmissive structure includes a plurality of optical collimators, and wherein the light exit portions of the optical collimators are closely packed together;
FIG. 4A is a side view of four LED-based light sources of a light source according to another embodiment, wherein the LED-based light sources are arranged in a spaced-apart arrangement;
FIG. 4B depicts the arrangement of the LED light source of FIG. 4A as viewed from above (i.e., in plan view);
FIG. 4C depicts a light exit portion of the optically transmissive structure of FIG. 4A, wherein the optically transmissive structure includes a trapezoidal light guide;
fig. 5 depicts an arrangement of optically transmissive structures of a light source according to an embodiment; and
fig. 6 depicts an arrangement of optically transmissive structures of a light source according to another embodiment.
Detailed Description
The invention provides a light source comprising a plurality of LED light sources and a method for manufacturing the same. Embodiments may be particularly relevant for applications requiring high or increased brightness of light from a relatively small and/or efficient light source.
The examples employ the following concepts: light of increased brightness is obtained from a semiconductor light source having a mixing box with a small light output portion, and then light is emitted again via the secondary light emission/exit surface of the optical structure. By adapting the optical structure to emit light via a more concentrated (e.g., smaller) area than the area occupied by the semiconductor light sources, embodiments may avoid the need to closely pack/space the semiconductor light sources. Furthermore, enabling the semiconductor light sources to be spaced apart (while maintaining a small light emission surface of the light sources) can help alleviate addressability limitations associated with current density in the conductive addressing tracks.
Therefore, applications have been proposed for high brightness LED light sources having a light output section with a smaller area than the light generating portion of the light source. By arranging an optically transmissive structure (also referred to as an "optical structure") to collect and confine light from a high brightness LED light source and then re-emit light via a secondary light emission surface, a pixelated light source may be achieved in which the light emission surface comprises closely packed pixels outputting light from the respective LED light sources. By spacing the LED light sources (e.g., less closely packed) such that they occupy a footprint area greater than the area of the secondary light emission surface, pixelated light sources having high brightness properties and small spacing between light emitting pixels can be realized with LED light sources that are freed from the constraint of having to be closely packed with near-zero spacing therebetween.
As used herein, the term perpendicular refers to substantially orthogonal to the surface of the substrate. As used herein, the term lateral refers to being substantially parallel to the surface of the substrate. Furthermore, the terms (e.g., above, below, top, bottom, etc.) describing a position or location are to be interpreted in conjunction with the orientation of the structures illustrated in the figures.
The figures are purely diagrammatic and it will therefore be appreciated that the dimensions of the features are not drawn to scale. Thus, the illustrated thickness of any layer should not be considered limiting. For example, a first layer drawn thicker than a second layer may in practice be thinner than the second layer.
FIG. 2 depicts a light source according to an embodiment of the present invention. More specifically, fig. 2A is a side view of two LED-based light sources of the light source, wherein the LED-based light sources are arranged in a spaced-apart arrangement. Fig. 2B depicts the arrangement of the LED light sources as viewed from above (i.e., in plan view). Fig. 2C depicts a light exit portion of an optically transmissive structure, wherein the optically transmissive structure comprises a plurality of optical fibers, and wherein the light exit portions of the optical fibers are closely packed.
The LED-based light sources are similar to the light sources shown in fig. 1A and 1B in that they each include an LED 12 (on a die substrate 14) within a mixing box 16, the mixing box 16 having an aperture 18 (or light output 18) that has a smaller area than the LED 12. As already described in detail in the background section above, such LED-based light sources exhibit increased brightness and may therefore be referred to as "high brightness LED light sources".
As shown in fig. 2A, each LED light source has one end of an optical fiber 20 positioned to cover its light output section 18. In this way, light from each LED is output from its respective light output 18 and input into the associated optical fibre. The input light is transmitted along the optical fiber 20 and is output from the other end 22 (i.e., the light exit portion 22) of the optical fiber 20.
Accordingly, it will be appreciated that each optical fiber 20 collects light output from the respective LED light source and confines the light by total internal reflection such that the light is reflected at the other end of the optical fiber 22 towards the light exit section 22.
As illustrated in fig. 2A, the optical fiber 20 is flexible or may be shaped to enable the light exit section 22 to be oriented in a different direction than the light output section 18. Thus, light from the LED light source may be transmitted along the optical fiber 20 and output from the optical fiber 20 at different locations and/or directions (which may be closer to a desired light exit plane and/or location, for example).
As depicted in FIG. 2B, the LED-based light sources 10 are arranged in a 2-dimensional array such that they are separated by a predetermined separation distance SLEDSpaced apart from each other. As a result, the total surface space or area A occupied by the LED-based light source 10LEDSI.e. the footprint area a of the LED-based light source 10LEDSIncluding the entire area surrounding the LED light source 10 and the space therebetween.In other words, the footprint area A of the LED-based light source 10LEDSEqual to the total width W occupied by the LED-based light source (and the space therebetween)LEDSMultiplied by the total length L occupied by the LED-based light source (and the space therebetween)LEDSThis can be represented by equation ALEDS= WLEDSX LLEDSAnd (4) showing.
In contrast, as depicted in fig. 2C, the light exit parts 22 of the optical fibers 20 are closely packed together so that there is almost no gap between the adjacent light exit parts 22. As a result, the total space or area A occupied by the light exit part 22OUTI.e. the footprint area A of the light exit part 22OUTIs smaller than the footprint area A of the LED-based light source 10LEDS. In other words, the total area A of the light emitting section 22OUTEqual to the total width W occupied by the light exit portions 22 (and any space therebetween)OUTMultiplied by the total length L occupied by the light exit portions 22 (and any space therebetween)OUTThis can be represented by equation AOUT= WOUTX LOUTAnd AOUT <ALEDSAnd (4) showing.
Thus, it will be appreciated that the plurality of optical fibers 20 provides a reduction in the light exit/emission surface size of the light source when compared to the space/area occupied by the LED light source 10. Furthermore, the ability to require more space for the LED light source 10 than the light exit/emitting surface (i.e., the light exit portion 22) can enable the use of more powerful LED light sources and/or greater spacing between LED light sources.
Thus, the embodiment depicted in fig. 2 provides a high brightness light source comprising a plurality of high brightness LED light sources 10 outputting light into a light confining optically transmissive structure (formed by a plurality of optical fibers 20) and then outputting the light via a light exit/emission surface having an area smaller than the footprint area of the LED light sources 10. Furthermore, the optical fibers 20 of the optical element may be adapted to redirect light from the LED light source 10 such that the light output direction/orientation and/or position is changed or designed to enable tiling with other light sources.
Turning now to FIG. 3, depicted therein is a light source in accordance with an embodiment of the present invention. More specifically, fig. 3A is a side view of four LED-based light sources of the light source, wherein the LED-based light sources are arranged in a spaced-apart arrangement. Fig. 3B depicts the arrangement of the LED light sources as viewed from above (i.e., in plan view). Fig. 3C depicts a light exit portion of an optically transmissive structure, wherein the optically transmissive structure comprises a plurality of optical collimators, and wherein the light exit portions of the optical collimators are closely packed together.
The LED-based light sources are similar to the light sources shown in fig. 1A and 1B in that they each include an LED 12 (on a die substrate 14) within a mixing box 16, the mixing box 16 having an aperture 18 (or light output 18) that has a smaller area than the LED 12. However, in the present embodiment, the light output section 18 of each LED-based light source comprises an optical enhancement material. More specifically, the optical enhancement material 18 includes a "color conversion filler" such as a luminescent ceramic material or a phosphorescent material. This may further help to maintain etendue of the lateral emission region.
As shown in fig. 3A, each LED light source has one end of the respective optical collimator 30 positioned to cover the light output section 18 thereof. In this manner, light from each LED is output from its respective light output section 18 and input into the associated optical collimator 30. The input light is transmitted along the optical collimator 30 and is output from the other end 32 (i.e., the light exit part 32) of the optical collimator 30.
It will therefore be appreciated that each optical collimator 30 collects light output from the respective LED light source and confines the light by total internal reflection such that the light is reflected at the other end of the optical collimator 30 towards the light exit 32.
As illustrated in fig. 3A, the optical collimators 30 are curved (e.g., non-linear along their entire length) to enable the light exit sections 32 of the optical collimators 30 to be laterally offset from the light output section 18. Thus, light from the LED light sources may be transmitted along the optical collimator 30 and output from the light exit portion 32 at different lateral positions and/or directions (which may be closer to a desired light exit plane and/or location).
As depicted in FIG. 3B, the LEDs 12 are arranged in a 2-dimensional array such thatThey are separated by a predetermined separation distance SLEDSpaced apart from each other. As a result, the total surface space or area A occupied by the LEDs 12LEDSI.e. the footprint area A of the LED 12LEDSIncluding the entire area surrounding the LEDs and the space therebetween. In other words, the footprint area A of the LED 12LEDSEqual to the total width W occupied by the LEDs (and the spaces therebetween)LEDSMultiplied by the total length L occupied by the LEDs (and the space therebetween)LEDSThis can be represented by equation ALEDS=WLEDSX LLEDSAnd (4) showing.
In contrast, as depicted in fig. 3C, the light exit portions 32 of the optical collimator 30 are closely packed together such that there is only a small separation distance S between adjacent light exit portions 32OUT. As a result, the total space or area a occupied by the light exit part 32OUTI.e. the footprint area A of the light exit part 32OUTIs smaller than the covered area A of the LED 10LEDS. In other words, the total area A of the light emitting part 32OUTEqual to the total width W occupied by the light emitting parts 32 (and the space therebetween)OUTMultiplied by the total length L occupied by the light-emitting parts 32 (and the space therebetween)OUTThis can be represented by equation AOUT= WOUTX LOUTAnd AOUT <ALEDSAnd (4) showing.
It will therefore be appreciated that the arrangement of the plurality of optical collimators 30 provides a reduction in the size of the light exit/emission surface of the light source when compared to the space/area occupied by the LEDs. The ability to have the space required for the LEDs larger than the space required for the light exit/emission surface (i.e., the light exit portion 32) may enable the use of more powerful LEDs and/or greater spacing between LEDs.
Thus, the embodiment depicted in fig. 3 provides a high brightness light source comprising a plurality of high brightness LED light sources 10 outputting light into a light confining optically transmissive structure (formed by a plurality of optical collimators 30) and then outputting the light via a light exit/emission surface having an area smaller than the footprint area of the LED light sources 10. Furthermore, the optical collimators 30 of the optically transmissive structures redirect the light from the LED light sources 10 such that the light output positions are changed or designed to enable tiling with other light sources.
Turning now to fig. 4, there is depicted a light source according to another embodiment of the present invention. More specifically, fig. 4A is a side view of four LED-based light sources of the light source, wherein the LED-based light sources are arranged in a spaced-apart arrangement. Fig. 4B depicts the arrangement of the LED light sources as viewed from above (i.e., in plan view). Fig. 4C depicts a light exit portion of an optically transmissive structure, wherein the optically transmissive structure comprises a trapezoidal light guide.
The light source is similar to the light source of fig. 3. However, there are two significant modifications, which are: (i) the fresnel structure 40 is adapted to cover/overlap the light output section 18 of each LED light source 10; and (ii) the optically transmissive structure comprises a single trapezoidal light guide 50.
In more detail, a first face 55 of the parallel faces of the light guide 50 is arranged facing downwards and covering the light output 18 of the LED light source 10. In this way, light from each LED is output from its respective light output 18 and input into the light guide via a first, downwardly facing face 55 of the light guide 50. The input light is transmitted through the light guide 50 and output through the opposite, upwardly facing face 60 of the light guide 50. Thus, the upwardly facing face 60 of the light guide 50 may be referred to as the light exit surface 60 of the light guide 50.
It will therefore be appreciated that the light guide 50 collects light output from the LED light sources it covers and confines the light by total internal reflection so that the light is reflected at the opposite face of the light guide 50 towards the light exit surface 60.
As depicted in FIG. 4B, the LEDs 12 are arranged in a 2-dimensional array such that they are separated by a predetermined separation distance SLEDSpaced apart from each other. Thus, the total surface area A occupied by the LEDs 12LEDSI.e. the footprint area A of the LED 12LEDSIncluding the entire area surrounding the LEDs and the space therebetween. In other words, the footprint area A of the LED 12LEDSEqual to the total width W occupied by the LEDs (and the space between them)LEDSMultiplied by the total length L occupied by the LEDs (and the space between them)LEDSThis can be represented by equation ALEDS= WLEDSX LLEDSAnd (4) showing.
In contrast, as depicted in FIG. 4C, of light guide 50The light exit surface 60 has a total area that is less than the footprint area A of the LEDLEDS. In other words, the total area A of the light exit surface 60OUTIs equal to the total width W of the light exit surface 60OUTMultiplied by the total length L of the light exit surface 60OUTThis can be represented by equation AOUT= WOUTX LOUTAnd AOUT <ALEDSAnd (4) showing.
Thus, it will be appreciated that the light guide 50 provides a reduction in the size of the light exit/emission surface of the light source when compared to the space/area occupied by the LEDs.
The embodiment depicted in fig. 4 thus provides a high brightness light source comprising a plurality of high brightness LED light sources 10 outputting light into a light confining optical element and then outputting the light via a light exit/emission surface having an area smaller than the footprint area of the LED light source.
Furthermore, it will be appreciated that the embodiment of fig. 4 is preferably arranged to include micro-optics on top of the LED that redirect light towards the light exit surface 60 of the light guide 50, ideally with as little optical loss as possible. If the light is not redirected, some of the light may escape at the edges of the trapezoidal light guide 50 (where total internal reflection does not occur for certain angles of incidence). Such micro-optics may be an asymmetric prism foil (similar to that used for conventional flash lamps) that may direct light to another angle from normal.
Reference is now made to fig. 5 and 6, where first and second potential arrangements of optically transmissive structures, respectively, are depicted.
In fig. 5, the optically transmissive structure includes four waveguides 100, each of which covers at one end the light output of a respective LED light source 110. The four LED light sources are arranged in a 2x2 array. The waveguides 100 are shaped (e.g., curved) such that their other ends (i.e., their light exit ends) are spaced apart and arranged in a 1x4 array (i.e., in a single row or row).
The total surface area A occupied by the LED light sources 110LEDSI.e. the footprint area A of the LED light source 110LEDSEqual to the total width W occupied by LED light sources 110LEDSMultiplied by the LED light source110 total length LLEDSThis can be represented by equation ALEDS=WLEDSX LLEDSAnd (4) showing.
The total space or area A occupied by the light exit end as a result of the arrangement of the waveguide 100OUTI.e. the area A of the covered area of the light emitting endOUTSmaller than the footprint area A of the LED's light source 110LEDS. In other words, the total area A of the light emitting endOUTEqual to the total width W occupied by the light emitting ends (and the space therebetween)OUTMultiplied by the total length L occupied by the light-emitting ends (and the space therebetween)OUTThis can be represented by equation AOUT= WOUTX LOUTAnd AOUT <ALEDSAnd (4) showing.
Similarly, in fig. 6, the optically transmissive structure again comprises four waveguides 100, each covering at one end the light output of a respective LED light source 110. The four LED light sources are arranged in a 2x2 array, and the waveguide 100 is shaped (e.g., bent) such that their other ends (i.e., their light exit ends) are closely packed together in a 4x1 array (i.e., in a single row or row). In this way, there is little gap between adjacent light exit ends of the waveguide 100.
The total surface area A occupied by the LED light sources 110LEDSI.e. the footprint area A of the LED light source 110LEDSEqual to the total width W occupied by the LED light sources 110LEDSMultiplied by the total length L occupied by the LED light source 110LEDSThis can be represented by equation ALEDS=WLEDSX LLEDSAnd (4) showing.
However, as depicted in fig. 6, the total space or area a occupied by the light exit endOUTI.e. the area A of the covered area of the light emitting endOUTEqual to or smaller than the footprint area A of the light source 110 of the LEDLEDS. In other words, the total area A of the light emitting endOUTEqual to the total width W occupied by the light emitting ends (and the space therebetween)OUTMultiplied by the total length L occupied by the light-emitting ends (and the space therebetween)OUTThis can be represented by equation AOUT= WOUTX LOUTAnd AOUT <ALEDSAnd (4) showing.
The arrangement of fig. 5 and 6 enables reshaping of the original light source arrangement. In addition, it should be noted that the four LEDs as illustrated in FIG. 6 may actually be one larger LED. And thus the arrangement of figure 6 enables reshaping of a single light source.
It should be understood that other reshaping arrangements may be employed. For example, a 4x4 array of LEDs may be morphed into a 2x8 array of light emitting surfaces (or any other arbitrary shape).
Those skilled in the art will appreciate that other variations of the disclosed embodiments can be understood and implemented.
For example, the LED light source of the present disclosure may be any type of LED, such as flip-chip type (thin film flip chip), patterned sapphire substrate, top-connected/top-emitting, top-bottom connected. In addition, the light source may be used as a bare die or packaged.
The light output portion (or light emitting region) of the LED light source refers to a region through which light is output (or emitted) from the LED. Thus, the cavity or cavities of the LED light source may extend towards the light output section. The light output may for example be a region of a growth substrate (e.g. sapphire). Further, the light output direction is generalized to a single direction (e.g., vertical in the drawing) along which light is output from the light output section. However, it should be understood that not all of the light output from the light output section may be precisely output in the output direction. Hence, the light output direction should be understood to refer to the general direction along which light is output from the light output section (e.g. extending away from the surface of the light output section).
The light source may further comprise a layer of optical enhancing material at least partially covering the light output/exit portion(s) of the optically transmissive structure.
Further, if an embodiment includes multiple cavities, some or all of the cavities may include (e.g., be filled with) different materials. As an example, some cavities may be filled with a first type of phosphor (e.g., converting blue to white) and other cavities may be filled with another type of phosphor (e.g., converting blue to red).
Embodiments may be employed in the field of automotive lighting and other fields/applications where high brightness lighting is required.
In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims shall not be construed as limiting the scope.

Claims (12)

1. A light source, comprising:
a plurality of LED light sources arranged in a 2-dimensional array on a planar area, each of the plurality of LED light sources having: a semiconductor diode structure adapted to generate light; and a light output section over the semiconductor diode structure adapted to output light from the semiconductor diode structure;
each of the plurality of LED light sources further comprises a light reflecting structure at least partially enclosing a side surface of the semiconductor diode structure and adapted to reflect light from the semiconductor diode structure towards the light output section; and the light reflecting structure has an aperture formed on a light output portion of the semiconductor diode structure; and
an optically transmissive structure overlapping the light output sections of the plurality of LED light sources for receiving light therefrom and having a light exit section adapted to output the received light, wherein the area of the light exit section of the optically transmissive structure is smaller than the footprint area of the plurality of LED light sources, the optically transmissive structure comprising one or more optical collimators,
wherein the area of the aperture is smaller than the area of the semiconductor diode structure, an
Wherein the collimator covers a portion of a light output section of the semiconductor diode structure on which the aperture is formed.
2. The light source according to claim 1, wherein the optically transmissive structure is adapted to confine the received light by total internal reflection and thus reflect the received light towards the light exit section.
3. The light source of claim 1, wherein the optically transmissive structure comprises a plurality of optical fibers positioned on top of the light output sections of the plurality of LED light sources.
4. The light source of claim 1, wherein the aperture formed in the light reflecting structure comprises an optical enhancement material.
5. The light source of any of claims 1 to 4, wherein the light output of at least one of the plurality of LED light sources comprises an optical enhancement material.
6. The light source according to any one of claims 1 to 4, further comprising a layer of optical enhancing material at least partially covering the light exit portion of the optically transmissive structure.
7. The light source of any of claims 1 to 4, wherein the optically transmissive structure further comprises a Fresnel structure at least partially overlapping the light output of the plurality of LED light sources.
8. An automotive lamp comprising a light source according to any one of the preceding claims.
9. A projection lamp comprising a light source according to any one of claims 1 to 7.
10. A method of manufacturing a light source comprising a plurality of LED light sources arranged in a 2-dimensional array over a planar area, each of the plurality of LED light sources having: a semiconductor diode structure adapted to generate light; and a light output section over the semiconductor diode structure adapted to output light from the semiconductor diode structure; the method comprises the following steps:
providing each of the plurality of LED light sources with a light reflecting structure at least partially enclosing a side surface of the semiconductor diode structure and adapted to reflect light from the semiconductor diode structure towards the light output section;
providing an aperture in the light reflecting structure of each of the plurality of LED light sources, the aperture being formed on the light output portion of the semiconductor diode structure,
providing an optically transmissive structure overlapping the light output portions of the plurality of LED light sources for receiving light from the light output portions of the plurality of LED light sources, the optically transmissive structure having a light exit portion adapted to output the received light,
wherein an area of the light exit portion of the optically transmissive structure is smaller than a footprint area of the plurality of LED light sources,
wherein the area of the light output section is smaller than the area of the semiconductor diode structure,
wherein the optically transmissive structure comprises one or more optical collimators, an
Wherein the collimator covers a portion of a light output section of the semiconductor diode structure on which the aperture is formed.
11. The method of claim 10, wherein the optically transmissive structure is adapted to confine the received light by total internal reflection and thereby reflect the received light towards the light exit section.
12. The method of claim 11, wherein the step of providing an optically transmissive structure comprises positioning a plurality of optical fibers on top of the light output of the plurality of LED light sources.
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